Lower Hutt, New Zealand
Lower Hutt, New Zealand

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Davies T.,University of Canterbury | Davies T.,Durham University | Beaven S.,University of Canterbury | Conradson D.,University of Canterbury | And 10 more authors.
International Journal of Disaster Risk Reduction | Year: 2015

Quantitative risk assessment and risk management processes are critically examined in the context of their applicability to the statistically infrequent and sometimes unforeseen events that trigger major disasters. While of value when applied at regional or larger scales by governments and insurance companies, these processes do not provide a rational basis for reducing the impacts of major disasters at the local (community) level because in any given locality disaster events occur too infrequently for their future occurrence in a realistic timeframe to be accurately predicted by statistics. Given that regional and national strategies for disaster reduction cannot be effective without effective local disaster reduction measures, this is a significant problem. Instead, we suggest that communities, local government officials, civil society organisations and scientists could usefully form teams to co-develop local hazard event and effects scenarios, around which the teams can then develop realistic long-term plans for building local resilience. These plans may also be of value in reducing the impacts of other disasters, and are likely to have the additional benefits of improving science development, relevance and uptake, and of enhancing communication between scientists and the public. © 2015 Elsevier Ltd.

Ryan M.T.,Victoria University of Wellington | Newnham R.M.,Victoria University of Wellington | Dunbar G.B.,Victoria University of Wellington | Vandergoes M.J.,GNS Science Ltd. | And 7 more authors.
Review of Palaeobotany and Palynology | Year: 2016

The occurrence of terrestrial palynomorphs in Quaternary marine sedimentary sequences allows for direct land-sea correlations and provides a means for transferring Marine Isotope Stage chronologies to terrestrial records that extend beyond the range of radiocarbon dating. Both of these important applications require an implicit assumption that the lag between pollen release and final deposition on the seafloor - here referred to as source-to-sink residence time - is negligible in relation to the chronological resolution of the sedimentary sequence. Most studies implicitly assume zero lag, and where studies do take palynomorph residence time into account, its magnitude is rarely quantified. In Westland, New Zealand, fluvial transport is the main source of delivery of terrestrial pollen offshore to the adjacent East Tasman Sea. We radiocarbon-dated organic matter carried and deposited by contemporary Westland rivers that drain catchments with varying degrees of disturbance. The ages obtained ranged widely from essentially modern (i.e., - 57 ± 22 cal yr BP) to 3583 ± 188 cal yr BP, suggesting that precisely constraining the residence time in this region is unlikely to be achieved. We also compared the timing of four palynomorph events characterising Westland's late Pleistocene, along with the well-dated Kawakawa/Oruanui Tephra (KOT), between marine core MD06-2991 and four terrestrial records from Westland. Critically, all palynomorph events and the KOT are chronologically indistinguishable with respect to the independently dated marine and terrestrial records, supporting the general principle of transferring the marine chronology onto the terrestrial records in this setting. In other regions, particularly those lacking the high soil production and erosion rates that characterise Westland, we suggest that similar tests of marine residence time should be conducted before assumptions of zero or negligible lag are invoked. © 2016 Elsevier B.V.

Breukers R.D.,Industrial Research Ltd. | Bartle C.M.,GNS Science Ltd | Edgar A.,Victoria University of Wellington
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2012

The fabrication of a series of novel, optically transparent, bulk plastic scintillators loaded with lithium methacrylate, and incorporating 2,5-diphenyloxazole and 5-phenyl-2-[4-(5-phenyl-1,3-oxazol-2-yl)phenyl]-1,3-oxazole fluorescent centres, is described. The attenuation length, photoluminescence, and both gamma ray and thermal neutron scintillation responses were compared over a range of lithium methacrylate concentrations. The maximum concentration corresponded to a weight percentage of lithium-6 of 0.63%. The photoluminescence shows a composite 2,5-diphenyloxazole and 5-phenyl-2-[4-(5-phenyl-1,3-oxazol-2-yl)phenyl]-1,3-oxazole broad band with vibronic features in the range 350-500. nm, and lifetimes in the range 0.9-2.7. ns. An increasing luminescence in a thermal neutron beam with increasing lithium-6 content is demonstrated. © 2012 Elsevier B.V.

Davies T.,University of Canterbury | McSaveney M.,GNS Science Ltd | Kelfoun K.,CNRS Magmas and Volcanoes Laboratory
Bulletin of Volcanology | Year: 2010

We propose a mechanical explanation for the low basal shear resistance (about 50 kPa) previously used to simulate successfully the complex, well-documented deposit morphology and lithological distribution produced by emplacement of the 25 km3 Socompa volcanic debris avalanche deposit, Chile. Stratigraphic evidence for intense basal comminution indicates the occurrence of dynamic rock fragmentation in the basal region of this large granular mass flow, and we show that such fragmentation generates a basal shear stress, retarding motion of the avalanche, that is a function of the flow thickness and intact rock strength. The topography of the Socompa deposit is realistically simulated using this fragmentation-derived resistance function. Basal fragmentation is also compatible with the evidence from the deposit that reflection of the avalanche from topography caused a secondary wave that interacted with the primary flow. © 2010 Springer-Verlag.

Procter J.N.,Massey University | Cronin S.J.,Massey University | Fuller I.C.,Massey University | Lube G.,Massey University | Manville V.,GNS Science Ltd.
Geology | Year: 2010

At 11:18 h (New Zealand time, GMT +12) on 18 March 2007 an impoundment of 0.01 × 106 m3 of tephra collapsed, releasing 1.3 × 106 m3 of water from Crater Lake at 2536 m elevation on Mount Ruapehu. The lahar traveled 200 km along the Whangaehu River. Aerial LiDAR surveys of the upper 62 km of flow path were made before and after the lahar. We present here the first large-scale quantification of the geomorphic impact of the dam-break flood along with the rates and controls on its sediment entrainment and deposition. The flood mobilized a net value of 2.5-3.1 × 106 m3 of boulders, gravel, and sand over the first 5 km of travel to form a lahar of at least 4.4 × 106 m3 passing instruments at 6.9 km. LiDAR volume-transfer calculations match dynamic measurements made. After a logarithmic increase in cumulative net sediment entrainment, the lahar appeared to reach its maximum sediment-carrying capacity at 22 km. Patterns of alternating sediment erosion and deposition occurred that dominantly reflect a combination of channel morphology and confinement on the local sediment-carrying capacity of the flow. © 2010 Geological Society of America.

Ryan M.T.,Victoria University of Wellington | Dunbar G.B.,Victoria University of Wellington | Vandergoes M.J.,GNS Science Ltd | Neil H.L.,NIWA Ltd | And 4 more authors.
Quaternary Science Reviews | Year: 2012

Paleo-vegetation records developed from marine sedimentary sequences offer considerable potential for examining changes in terrestrial climate beyond the range of 14C dating because they can be independently dated by δ 18O stratigraphy. Here we present the first pollen record of vegetation from a marine core site in the Tasman Sea, TAN0513-14 (42°18'S, 169°53'E), ~110 km west of New Zealand's South Island. An independent chronology provided by correlating the Globigerina bulloides δ 18O record at TAN0513-14 to a global isotope stack shows that the record extends back to 210 ka. Glacial to interglacial changes in palynomorph content are characterised by shrub and podocarp-broadleaf forest taxa respectively and are correlated with similar changes in the ca 150 kyr-long terrestrial pollen record from Okarito Pakihi (bog), 110 km to the south southeast. Both records are placed on the same timescale by matching variations in Dacrydium cupressinum and Fuscospora between sites, with a unique tie point provided by the ca 25.4 ka Kawakawa Tephra. Our Southern Hemisphere mid-latitude vegetation records show forest extent is greatest during periods of low ice volume, high mean annual sea surface temperature (MASST) and anti-phased with local insolation intensity. However, there are several features not attributable to changes in mean annual temperature. First, a fundamental change in forest composition occurred at Termination II (TII), with a loss of southern beech (Nothofagus) from the study area. Second, the amplitude of MASST change through MIS 5 is not reflected in corresponding changes in forest extent, suggesting other feature(s) of regional climate (seasonality, frostiness, ice cover) exert important controls over vegetation patterns at these latitudes. © 2012 Elsevier Ltd.

Davies T.R.H.,University of Canterbury | McSaveney M.J.,GNS Science Ltd | Boulton C.J.,University of Canterbury
Journal of Structural Geology | Year: 2012

As a confined static grain mass is increasingly stressed, elastic strain energy accumulates in the grains; when local stress somewhere exceeds grain strength, grain breakage radiates this stored energy to the surrounding grains as a brief high-intensity pulse of pressure energy. Local grain stresses in a stressed static fault-zone follow a known probability density distribution in which the maximum local grain stress resulting from a given applied stress increases with fault-plane area. Tectonic stress buildup on a fault increases the probability of local stresses sufficient to break grains. Brittle failure of a grain releases strain energy that can trigger cascading failure of a large fault at relatively low applied stress, culminating in fault rupture, if the fault strength distribution is sufficiently homogeneous. Such ruptures can occur at lower driving stresses in larger faults. This process correctly explains the magnitude of the failure stress of the peninsula segment of the San Andreas fault, so may significantly affect fault rupture strength. Grain fragmentation also plays a significant role in dynamic fault friction; in dense comminuting granular flows, grain fragmentation causes continuous recycling of elastic-strain energy. During cataclastic fault slip, widespread grain comminution thus generates and maintains an intense high-frequency elastic energy field that causes dynamic weakness. This process is sufficiently powerful to explain the magnitude of the dynamic slip resistance of the San Andreas fault. © 2011 Elsevier Ltd.

Daly M.,GNS Science Ltd | Johnston D.,GNS Science Ltd
Journal of Applied Volcanology | Year: 2015

The Auckland Engineering Lifelines Project (A.E.L.P.) was initiated by the Auckland Regional Council, New Zealand, in 1996 to reduce the damage to and downtime of utilities such as water, wastewater, gas, power, etc., resulting from a variety of natural and technological hazards. A key initial project was a volcanic risk assessment. This paper describes the methodology that was developed to specifically assess the volcanic risk to lifelines from the Auckland Volcanic Field and distal volcanic centres in the central North Island, the application of the risk assessment and further developments beyond the initial project. © 2015 Daly and Johnston.

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